1. Field of the Invention
The invention relates to an earphone jack, more particularly to an earphone jack that has a reliable construction.
2. Description of the Related Art
FIGS. 1 to 3 illustrate a conventional earphone jack 1 for use with a mating plug 2 of an electronic apparatus. The earphone jack 1 includes an insulative housing 11, and conductive first, second, third and fourth contact members 12, 13, 14, 15 mounted on the insulative housing 11.
The insulative housing 11 has opposite front and rear ends 1121, 1122, and is formed with a plug insertion hole 112 that extends along a hole axis (A) from the front end 1121 to the rear end 1122. The plug insertion hole 112 has a front hole section 1130 adjacent to the front end 1121 of the insulative housing 11, and a rear hole section 1131 adjacent to the rear end 1122 of the insulative housing 11. The insulative housing 11 is further formed with a first contact mounting portion 114 adjacent to the front end 1121 of the insulative housing 11, and a second contact mounting portion 115 between the first contact mounting portion 114 and the rear end 1122 of the insulative housing 11.
The first contact member 12 is mounted on the insulative housing 11 at the first contact mounting portion 114, and includes a plug contacting portion 121 that extends into the front hole section 1130, and a contact tab 122 that extends horizontally away from the insulative housing 11.
The second contact member 13 is mounted on the insulative housing 11 at the second contact mounting portion 115, and includes a plug contacting portion 131 that extends into the front hole section 1130, and a contact tab 132 that extends horizontally away from the insulative housing 11.
The third contact member 14 is mounted in the insulative housing 11, and has a frame portion 141 disposed in the plug insertion hole 112, and a resilient portion 142 extending upwardly and obliquely from the frame portion 141. A contact tab 1411 extends from the frame portion 141 and outwardly of the insulative housing 11.
The fourth contact member 15 is mounted in the rear hole section 1131 of the plug insertion hole 112, and cooperates with the third contact member 14 to form a switch mechanism. Particularly, when the plug 2 is not inserted into the plug insertion hole 112, a tip of the resilient portion 142 contacts the fourth contact member 15 to result in a closed circuit condition, as best shown in FIG. 2. A contact tab 151 extends from the fourth contact member 15 and outwardly of the insulative housing 11.
Referring to FIG. 3, when the plug 2 is inserted into the plug insertion hole 112, the plug contacting portions 121, 131 of the first and second contact members 12, 13 and the resilient portion 142 of the third contact member 14 contact different parts of the plug 2 to effect signal transmission. At the same time, the resilient portion 142 of the third contact member 14 is moved away from the fourth contact member 15 to result in an open circuit condition.
The following are some of the drawbacks of the aforesaid conventional earphone jack 1:                1. In view of the cantilever design of the plug contacting portions 121, 131 of the first and second contact members 12, 13, the plug contacting portions 121, 131 are liable to deform after repeated insertion and removal of the plug 2, which can lead to poor electrical contact with the plug 2.        2. The resilient portion 142 is prone to break away from the frame portion 141 of the third contact member 14 due to stress concentration at the juncture of the frame and resilient portions 141, 142 after repeated insertion and removal of the plug 2.        3. The retention force attributed to the resilient portion 142 and acting on the plug 2 is relatively weak due to the small contact area therebetween.        